H-frame connection between fan case and core housing in a gas turbine engine

Abstract

A gas turbine engine includes a fan rotor driven by a fan drive turbine about an axis through a gear reduction to reduce a speed of the fan rotor relative to a speed of the fan drive turbine. A fan case surrounds the fan rotor, and a core engine with a compressor section, including a low pressure compressor. The fan rotor delivers air into a bypass duct defined between the fan case and the core engine. A rigid connection between the fan case and the core engine includes a plurality of H-frame connecting members rigidly connected to the fan case, and to the core engine. The H-frame connecting members each are defined by two rigid legs which extend between the fan case and to the core engine, along directions which are generally parallel to each other. A plurality of non-structural fan exit guide vanes and the non-structural fan exit guide vanes are provided with an acoustic feature to reduce noise. The non-structural fan exit guide vanes are rigidly mounted to at least one of the fan case and the core engine.

What is claimed is: 
     
       1. A gas turbine engine comprising:
 a fan rotor driven by a fan drive turbine about an axis through a gear reduction to reduce a speed of said fan rotor relative to a speed of said fan drive turbine; 
 a fan case surrounding said fan rotor, and a core engine with a compressor section, including a low pressure compressor; 
 said fan rotor delivering air into a bypass duct defined between said fan case and said core engine, and a rigid connection between said fan case and said core engine including a plurality of H-frame connecting members rigidly connected to said fan case, and to said core engine, the H-frame connecting members each being defined by two rigid legs which extend between said fan case and to said core engine, along directions which are generally parallel to each other; and 
 a plurality of non-structural fan exit guide vanes and said non-structural fan exit guide vanes being provided with an acoustic feature to reduce noise, said non-structural fan exit guide vanes being rigidly mounted to at least one of the fan case and the core engine. 
 
     
     
       2. The gas turbine engine as set forth in  claim 1 , wherein said acoustic feature includes said non-structural fan exit guide vanes being formed with chambers and a covering perforated face sheet. 
     
     
       3. The gas turbine engine as set forth in  claim 1 , wherein there are also structural fan exit guide vanes rigidly secured to both said fan case and said core engine, and said structural fan exit guide vanes include greater than 0 and less than 55% of a total number of fan exit guide vanes including the non-structural fan exit guide vane. 
     
     
       4. The gas turbine engine as set forth in  claim 3 , wherein said structural fan exit guide vanes include 15-30% of the total fan exit guide vanes. 
     
     
       5. The gas turbine engine as set forth in  claim 3 , wherein said core engine includes a fan intermediate case forward of said low pressure compressor, and said structural fan guide vanes are rigidly connected to said fan intermediate case, and said core engine including a compressor intermediate case intermediate said low pressure compressor and a high pressure compressor, and said H-frames are secured to said compressor intermediate case. 
     
     
       6. The gas turbine engine as set forth in  claim 1 , wherein there are two of said H-frames. 
     
     
       7. The gas turbine engine as set forth in  claim 1 , wherein there are four of said H-frames, with two of said H-frames being aligned at top dead center and bottom dead center and the other two H-frames being generally spaced by 90 degrees from H-frame at top dead center and said H-frame at bottom dead center. 
     
     
       8. The gas turbine engine as set forth in  claim 1 , wherein there are four of said H-frames, with two of said H-frames being spaced by 45 degrees from top dead center, and two of said H-frames being spaced by 45 degrees from bottom dead center. 
     
     
       9. The gas turbine engine as set forth in  claim 1 , wherein there are two of said H-frames, and two radial struts connecting said fan case to said core engine. 
     
     
       10. The gas turbine engine as set forth in  claim 1 , wherein there are two of said H-frames, and two A-frames, wherein each of said A-frames including a pair of legs rigidly connected at a connection point to said fan case, and each leg in said pair extending away from said connection point in opposed circumferential directions to be connected to said core engine to form an A-shape. 
     
     
       11. The gas turbine engine as set forth in  claim 1 , wherein said pair of rigid legs in said plurality of H-frames being spaced from each other by a first distance, and said core housing having a diameter at a connection location to said H-frames, and said diameter being greater than said distance. 
     
     
       12. The gas turbine engine as set forth in  claim 1 , wherein said low pressure compressor has four to six stages. 
     
     
       13. A gas turbine engine comprising:
 a fan rotor driven by a fan drive turbine about an axis through a gear reduction to reduce a speed of said fan rotor relative to a speed of said fan drive turbine; 
 a fan case surrounding said fan rotor, and a core engine with a compressor section, including a low pressure compressor; 
 a plurality of H-frames each being defined by two rigid legs which extend between said fan case and to said core engine, along directions which are generally parallel to each other, wherein said pair of rigid legs in said plurality of H-frames being spaced from each other by a first distance, and said core housing having a diameter at a connection location to said H-frames, and said diameter being greater than said distance; and 
 a plurality of fan exit guide vanes rigidly connected to said fan case, and connected to said core engine. 
 
     
     
       14. The gas turbine engine as set forth in  claim 13 , wherein there are structural fan exit guide vanes and non-structural fan exit guide vanes provided with an acoustic feature to reduce noise. 
     
     
       15. The gas turbine engine as set forth in  claim 13 , wherein said low pressure compressor has four to six stages. 
     
     
       16. The gas turbine engine as set forth in  claim 13 , wherein there are two of said H-frames connecting said fan case to said core engine. 
     
     
       17. The gas turbine engine as set forth in  claim 13 , wherein there are four of said H-frames, with two of said H-frames being aligned at top dead center and bottom dead center and the other two H-frames being generally spaced by 90 degrees from H-frame at top dead center and said H-frame at bottom dead center. 
     
     
       18. The gas turbine engine as set forth in  claim 13 , wherein there are four of said H-frames, with two of said H-frames being spaced by 45 degrees from top dead center, and two of said H-frames being spaced by 45 degrees from bottom dead center. 
     
     
       19. The gas turbine engine as set forth in  claim 13 , wherein there are two of said H-frames, and two radial struts connecting said fan case to said core engine. 
     
     
       20. The gas turbine engine as set forth in  claim 13 , wherein there are two of said H-frames, and two A-frames, wherein each of said A-frames including a pair of legs rigidly connected at a connection point to said fan case, and each leg in said pair extending away from said connection point in opposed circumferential directions to be connected to said core engine to form an A-shape.